Experimental Study And Numerical Analysis On Fatigue Strength Of Parallel Wire Based On Corrosion Classification

For modern system of cable supported Bridges, the cable systems are the main bearing structures.A large number of engineering examples show that corrosion fatigue damage happens easily during the process of bridge service in cyclic loading and synergistic interaction of corrosion environment, the real reasons that caused fractures are the mechanical property deterioration of wires and bearing capacity decrement of wires caused by wire corrosion or corrosion fatigue, which have a serious threat to the safety of bridge structures.To conduct the further research of bearing capacity and fatigue life of corrosion classification steel wires,not only cable security can be ensured during the process of bridge service, but also cable replacement can be carried out at the right time, reduce the economic loss, prolong the service life of bridge structures which is the main purpose of this paper.The main research content summarized as follows:(1) This paper studied the corrosion characteristics of parallel wires, wire corrosion process has been also analyzed. Combined with the results of artificial accelerated corrosion test, the corrosion level of steel wires were classified which provided the basis for corrosion fatigue performance test of steel wires under the corrosion classification.(2) The statistics analysis of three dimensional size of the corrosion pit were conducted which including depth, length and width of the distribution features.Then the finite element method was used for numerical analysis about typical semi-elliptical corrosion pit of stress concentration coefficient systematically.(3) Fatigue tests were carried out on the steel wire with different corrosion levels, it is concluded that the fatigue life of S-N curve, then studied the influences of degree of corrosion fatigue life of steel wire.Combined with the result of corrosion fatigue test and image analysis of wire fracture based on scanning electron microscopy, corrosion fatigue fracture mechanism of steel wire has been studied. Stress intensity factor with surface crack were studied which obtained the unification of the geometric correction factor expression of crack propagation under tensile load.Residual strength of steel wire with surface crack damage were also studied.(4) Corrosion fatigue process and the crack formation-propagation process of steel wire has been studied.Combined with the characteristics of corrosion fatigue damage, the corrosion fatigue life of the parallel wire evaluation calculation method has been studied by stages.